Inflatable, disposable dunnage bags comprise a relatively inexpensive and easily useable means of stabilizing cargo or freight disposed within cargo holds, containers, box-cars, or trailers of aircraft, trucks, trains, ships, and the like, so as to effectively prevent damage to such goods which would be likely to occur if the goods were not otherwise secured or tied down within the cargo hold or the like since the goods would be subjected to shifting movements within the cargo hold in response to movements of the particular transportation vehicle during shipping or transport. As is well known and conventionally practiced, inflatable dunnage bags are placed between individual, adjacent cargo items or pieces, or between the individual cargo pieces and the side walls of the vehicle which define the cargo hold, in an initially deflated condition and are then subsequently inflated with, for example, compressed air to a predetermined pressure value which is of course below the bursting pressure limit of the bag. Most bags which are conventionally used are specifically constructed so as to withstand bursting pressure values which are within the range of 12-30 psig.
Such conventional inflatable dunnage bags typically comprise a sealed inner plastic bladder or bag, which is fabricated, for example, from polyethylene, and an outer multiwalled or multi-layered paper bag that serves to protect the inner inflatable bag or bladder as well as to increase the bursting strength thereof. A valve is provided upon the inflatable bladder and extends through the outermost paper layer of the multi-layered paper bag so that the dunnage bag can be inflated and expanded when desired, that is, for example, for cargo securing purposes, with compressed air from an external compressed air source.
Manufacture of such conventional inflatable dunnage bags typically comprises folding a predetermined length of multi-layered kraft paper onto itself and about a longitudinal axis thereof such that the edges thereof can form an overlapping longitudinal seam which extends along the centerline of the bag, the result being a multi-walled paper tube having opposite open ends. The sealed plastic bladder is then inserted into the paper tube, and the tube ends are then folded over onto themselves so as to be subsequently glued or sewn closed thereby forming the completed dunnage bag.
It is thus appreciated that the fabrication of conventional dunnage bags as set forth hereinbefore presents several manufacturing problems. There is initially the problem of being capable of cutting a large number of paper plies during a single cutting operation. In addition, the manufacture of the bag is dependent upon or limited by the ability to stitch together the multiple layers of paper comprising the outer paper bag, as well as the capability of effectively folding and gluing the folded ends of the bag to the body portion of the bag such that the folded glued bonds do not subsequently fail or come undone. The construction of such multi-layered bags is also relatively labor intensive such that the greater the number of paper plies or layers, the greater the labor costs involved in fabricating the particular bag. Consequently, while it is desirable to attain an inflatable dunnage bag which exhibits a higher capacity to resist loading, or in other words, exhibits greater bursting pressure values as a result of being fabricated as a multi-layered structure, the cost of such a bag is higher than conventional bags with fewer layers of paper.
Consequently, in view of the foregoing, it was the object of the aforenoted related patent application, Ser. No. 08/654,307, filed on May 28, 1996, and entitled INFLATABLE COMBINATION CARGO PACKING BAG, to provide an improved inflatable dunnage bag which in fact exhibited higher bursting strength or pressure values and which was easier to manufacture in view of the fact that it was no longer necessary to sew or stitch together all of the paper plies or layers comprising the multi-layered paper tube of the dunnage bag, and in addition, the number of paper plies or layers which had to be glued together was also reduced. In accordance with that invention, the improved inflatable dunnage bag comprised a "bag within a bag" wherein a first inner bag, comprising an inflatable polyethylene bladder disposed within a two-ply paper bag, is subsequently inserted or encased within a second outer bag which may comprise two, four, or six paper plies. Consequently, while the same number of paper plies, for example, still comprise the completed dunnage bag, only those paper plies comprising the first inner bag need to be stitched or sewn, and the number of paper plies which need to be folded and glued in order to complete the manufacture of the dunnage bag, that is, those plies comprising the second outer bag, has been effectively reduced.
More particularly, with reference being made to FIG. 1 of the drawings, the inner or first inflatable bag is illustrated and generally indicated by the reference character 30. The bag 30 comprises a first end 32 and a second opposite end 34, and as can be appreciated from FIG. 2, with only first end 32 being shown, each end 32 and 34 is enclosed by means of a binding material 15 prior to the ends 32 and 34, and the binding material 15, being sewn together so as to close and seal the ends 32 and 34 of the bag 30. The longitudinal or lengthwise seam 36 of the bag 30 is formed by overlapping the longitudinal edge portions 37 and 39 of the bag 30, and once the seam 36 is formed and the ends 32 and 34 are closed and sealed, the inner bag 30 defines a closed and sealed interior which is able to be inflated by means of a suitable compressed gas, such as, for example, air.
As shown in FIG. 2, the inner or first inflatable bag 30 further comprises a thermoplastic bladder 10 which is fabricated as a continuous polyethylene tube that only requires heat sealing of its two opposite ends. The bladder 10 is initially disposed in a flattened state and is seen to comprise a first upper wall 10A and a second lower wall 10B which are sealed together at the opposite ends so as to form a sealed joint 12. The joint 12 is formed somewhat inwardly from the edge portion of the bladder 10 so as to form or define an end flap portion 13A. Paper plies 1 and 2 envelop the bladder 10, and in accordance with a first mode of constructing the composite bag 30, the first paper ply 1 is disposed atop the second paper ply 2, and the paper plies 1 and 2 are then folded in half so that each paper ply 1 and 2 has a first end 1C,2C and a second end 1D,2D in registry with each other, wherein the bladder 10 is disposed interiorly of, and enveloped by, the paper plies 1 and 2. in order to seal each end 32 and 34 of the composite inner bag 30, a binding 15 is disposed about the end 32, as illustrated, of the bag 30 so as to cover the paper plies 1 and 2, and the flap portion 13A of the bladder 10, and subsequently, suitable stitching 17 penetrates the composite end 32 of the bag 30 as defined by paper plies 1 and 2, bladder flap portion 13A, and binding 15. A similar technique is of course implemented with respect to inner bag end 34. In lieu of folding paper plies 1 and 2 in half, separate upper and lower paper plies 1 and 2 may be simply disposed atop each other such that the four separate and discrete paper plies 1 and 2 are simply secured and sealed together without any folding of the the paper plies being required.
In order to inflate the interior portion of the composite inner bag 30 with a suitable compressed gas, such as, for example, air, an inflation valve 20 is heat sealed within the upper wall 10A of the bladder 10 and projects outwardly through respective holes 25a, 25b, and 25c that are respectively provided within upper walls 2A, 1A, and 10A of the paper plies 2 and 1, and the bladder 10. While the composite inner bag 30 exhibits an average burst strength of approximately 8.0 psig, which is certainly adequate for light-duty or lightcargo applications, the composite inner bag 30 is adapted or intended to be disposed within a second outer bag comprising a tube fabricated from additional paper plies, for example, two, four, or six additional plies, whereupon insertion of the first inner bag 30 within the second outer paper bag, the ends of the second outer paper bag are then closed and sealed. Such an arrangement, comprising in effect a "bag within a bag", exhibits higher bursting strength or pressure values.
With reference therefore being made to FIG. 4, one end of the composite "bag within a bag" is disclosed, and it is to be understood that the other end of such composite bag comprises substantially identical structure. More particularly, it is seen that the first inner composite bag 30 of FIG. 2 has been inserted between two additional paper plies 3 and 4 whereby the completed or assembled composite bag 40 comprises a total of four paper plies, two of which initially comprise the first inner composite bag 30 and the other two comprising the outer composite bag 35. The paper plies 3 and 4 have respective first and second ends 3A,4A, and 3B,4B, with the second end 3B being folded and secured to the first end 3A by means of a glue bead 80, while the second end 4B is similarly folded and secured to the second end 3B by means of a glue bead 82. In order to complete the assembly of the composite bag 40, the outer surface 4C of paper ply 4 is coated with a suitable heat-sealable plastic, such as, for example, polyethylene 100, whereby through means of known heat-sealing techniques, second end 4B can be heat-sealed to first end 4A.
With comparison being made between the completed or assembled composite bag 40, comprising the first inner composite bag 30 and the second outer composite bag 35, and a conventional or prior art four-ply bag as shown in FIG. 3, it is readily appreciated that although the same number of glue beads are required for fabrication of the completed or assembled composite bag, the four-ply composite bag 40 shown in FIG. 4 is easier to fabricate than the conventional or prior art bag shown in FIG. 3 due to the reduced number of paper plies that are required to be simultaneously cut, folded, and glued together since the first inner composite bag 30 of the completed or assembled bag 40 of FIG. 4 is separately fabricated. In addition, having a reduced number of simultaneously folded plies reduces the tendency of the folded ends of the completed or assembled bag to unfold or fail. Still further, the bursting strength of the completed or assembled composite bag 40 is greater than that of the conventional or prior art bag shown in FIG. 3. It is lastly noted that while the first inner composite bag 30 is disposed interiorly or within the second outer composite bag 35, and wherein the inflation valve 20 of bag 30, as disclosed in FIG. 2, is not actually shown or illustrated in the completed or assembled composite bag 40 of FIG. 4, it is to be understood that the valve 20 does project outwardly through suitable holes, not shown, provided within paper plies 3 and 4 so as to be externally accessible in order to inflate the bladder of inner composite bag 30 with compressed gas from a suitable source of compressed gas, also not shown.
With reference now being made to FIG. 5, a further embodiment of the invention as disclosed within the aforenoted related patent application is illustrated, and it is seen that in accordance with this embodiment, the completed or assembled composite bag 40 comprises a total of six paper plies wherein two of such paper plies comprise or form a part of the first inner composite bag 30, including the inflatable bladder 10, and the remaining four paper plies comprise the second outer composite bag 35. The four paper plies 3-6 each have respective first and second ends 3A-6A and 3B-6B which are uniquely folded so as to reduce the number of folded ply ends and the number of glue beads needed to secure the ply ends, as compared to, for example, a conventional six-ply bag as shown in FIG. 7. More particularly, it is seen that in accordance with the invention embodiment of FIG. 5, the ends 6A and 6B. are heat-sealed together, while ends 5B, 4B, and 5A are glued together by glue beads 50. End 3B is folded so as to be interposed between first inner composite bag 30 and end 3A, while end 4A is freely interposed between ends 3A and 5A. Comparing this structure to that of FIG. 7, it is seen that all six paper plies 1-6 are all simultaneously folded back upon themselves as a collective group before the various ends are glued and heat-sealed together. As noted hereinbefore, the greater the number of paper plies to be folded, the more burdensome it becomes to in fact achieve such folding of the paper ply ends, to bind such folded plies with the glue, and to maintain the folded and glued plies in such folded and glued state due to the inherent tendency of the folded ends to unfold and separate from each other.
An eight-ply composite bag 40, constructed in a similar manner in accordance with the principles of the invention of the previously noted related patent application, is illustrated in FIG. 6 and is again seen to comprise the first inner composite bag 30, which includes the first two paper plies and the inflatable bladder, while the second outer composite bag 35 comprises paper plies 3-8. The paper plies 3-8 have respective first and second ends 3A-8A and 3B-8B which are also uniquely folded, glued, and heat-sealed so as to effectively reduce the number of plies needed to be glued and heat-sealed as compared to a conventional eight-ply dunnage bag as illustrated in FIG. 8. In order to glue and seal the conventional bag of FIG. 8, seven glue beads and one heat-seal are required, whereas in connection with the inventive bag of FIG. 6, only three glue beads and one heat-seal are required. More particularly, ends 7A and 7B are glued together by glue bead 60, while end 5B is glued to end 4B. and end 4B is glue to end 5A by glue beads 70. Ends 8A and 8B are heat-sealed together, while ends 6A and 6B are freely interposed between ends 7A and 5B, and ends 4A, 3B, and 3A are freely interposed between end 5A and first inner composite bag 30.
In light of the foregoing, it is therefore appreciated that the composite "bag within a bag" 40 of the aforenoted, previously filed patent application has certainly resolved some of the manufacturing problems or deficiencies characteristic of conventional dunnage bags, and has concomitantly achieved its initial objectives of enhancing the bursting strength or burst pressure values of the bags while maintaining the same number of paper plies comprising the bag. The reliability or structural integrity of the bag has of course been maintained while manufacture of the bag has been simplified by reducing the number of paper ply folds which need to be simultaneously handled, folded, glued, and heat-sealed. It has been realized, however, that dunnage bags of the aforenoted types, which have been disclosed within the particularly noted drawings and described hereinbefore, can be simplified still further without adversely affecting, for example, burst strength characteristics or values with respect to particularly desired load applications or requirements, and still further, that such dunnage bags can be rendered more cost-effective from a manufacturing or production point of view.
A need therefore exists in the art for multi-ply or multi-layered dunnage bags which can be simply manufactured, which exhibit predeterminedly adequate bursting strength or pressure values for predetermined load applications, which exhibit or provide ensured reliability and structural integrity, and which can be manufactured in a cost-effective manner by decreasing the cost per unit bag produced as a result of a reduction in connection with the materials required to produce such bags, that is, by reducing the number of paper plies required in connection with the fabrication of a particular dunnage bag which is adapted to be used in connection with a particular load application.